This invention relates to a toner supplying mechanism for a development unit including a development roller adapted to be positioned in an imaging apparatus such as a printer employing a so-called electrophotographic system so that toner particles are effectively supplied to the development roller.
Conventionally, known are imaging apparatuses such as an electric copying machine, a laser beam printer and the like capable of forming a visible image on a recording medium through a so-called electrophotographic system, wherein a photoconductive drum whose circumferential surface is covered with a photoconductive material layer is evenly charged with a predetermined polarity and exposed to light in accordance with image data for forming a latent image, toner particles are adhered to the surface of the photoconductive drum for making the latent image visible, the visible toner image is transferred to a recording medium such as a continuous-form recording sheet, and finally, the recording medium is subjected to pressure and high temperature so that the transferred image is fixed on the recording medium.
In this type of imaging apparatus, recently, each of the processes has been improved so as to be executed at high speed. Further, in view of the so-called space factor, it has become desirable to make the imaging apparatus small in size.
Further, in view of the high speed image forming operation, once the toner is supplied, it becomes preferable to execute the image forming operation as long as possible without an additional toner supplying operation.
In the development unit employed in the electrophotographic system, toner particles having been accommodated within a toner accommodating part thereof are attracted by magnetic force generated by a development roller which is located at a development portion at which a developing operation is to be executed. At the upper side of the toner accommodating part, a toner cartridge can be detachably provided. The toner cartridge, in which toner particles are housed is attached to the development unit, and the toner particles are supplied to the toner accommodating part from the toner cartridge.
In the toner accommodating part, a toner scraper comprises a plurality of arm members respectively connected to a shaft member which is arranged to be rotated. The toner particles having been supplied to the toner accommodating part are fed toward the development roller by means of the rotating arms. Accordingly, it is preferable to supply the toner particles within the arm rotating area of the arm members.
As described above, it is preferable to execute the image forming operation without the additional toner supplying operation and accordingly, it becomes preferable to make the toner accommodating part as large in volume as possible. However, since it is also preferable to make the whole volume of the imaging apparatus small, an inner wall of the accommodating part for connecting the toner cartridge and the toner accommodating part is usually formed in an inclined state so that the toner particles are fed toward the development roller by taking advantage of their fluidity. Therefore, the height of the imaging apparatus is made shorter as compared with the case in which the toner cartridge is located just over the toner scraper.
However; recently, since it has become desirable to make the imaging apparatus been even smaller, the outer form of the toner accommodating part is further limited, and the inclined angle of the inner wall often can not be designated for an effective supplying operation of the toner particles. In this case, a problem arises in that the toner particles remain on the inclined wall surface and are not fed toward the development roller.